/*
 * Require-CSS RequireJS css! loader plugin
 * 0.1.2
 * Guy Bedford 2013
 * MIT
 */

/*
 *
 * Usage:
 *  require(['css!./mycssFile']);
 *
 * Tested and working in (up to latest versions as of March 2013):
 * Android
 * iOS 6
 * IE 6 - 10
 * Chome 3 - 26
 * Firefox 3.5 - 19
 * Opera 10 - 12
 * 
 * browserling.com used for virtual testing environment
 *
 * Credit to B Cavalier & J Hann for the IE 6 - 9 method,
 * refined with help from Martin Cermak
 * 
 * Sources that helped along the way:
 * - https://developer.mozilla.org/en-US/docs/Browser_detection_using_the_user_agent
 * - http://www.phpied.com/when-is-a-stylesheet-really-loaded/
 * - https://github.com/cujojs/curl/blob/master/src/curl/plugin/css.js
 *
 */

define(function () {
    //>>excludeStart('excludeRequireCss', pragmas.excludeRequireCss)
    if (typeof window == 'undefined')
        return { load: function (n, r, load) { load() } };

    var head = document.getElementsByTagName('head')[0];

    var engine = window.navigator.userAgent.match(/Trident\/([^ ;]*)|AppleWebKit\/([^ ;]*)|Opera\/([^ ;]*)|rv\:([^ ;]*)(.*?)Gecko\/([^ ;]*)|MSIE\s([^ ;]*)|AndroidWebKit\/([^ ;]*)/) || 0;

    // use <style> @import load method (IE < 9, Firefox < 18)
    var useImportLoad = false;

    // set to false for explicit <link> load checking when onload doesn't work perfectly (webkit)
    var useOnload = true;

    // trident / msie
    if (engine[1] || engine[7])
        useImportLoad = parseInt(engine[1]) < 6 || parseInt(engine[7]) <= 9;
        // webkit
    else if (engine[2] || engine[8])
        useOnload = false;
        // gecko
    else if (engine[4])
        useImportLoad = parseInt(engine[4]) < 18;

    //>>excludeEnd('excludeRequireCss')
    //main api object
    var cssAPI = {};

    //>>excludeStart('excludeRequireCss', pragmas.excludeRequireCss)
    cssAPI.pluginBuilder = './css-builder';

    // <style> @import load method
    var curStyle, curSheet;
    var createStyle = function () {
        curStyle = document.createElement('style');
        head.appendChild(curStyle);
        curSheet = curStyle.styleSheet || curStyle.sheet;
    }
    var ieCnt = 0;
    var ieLoads = [];
    var ieCurCallback;

    var createIeLoad = function (url) {
        ieCnt++;
        if (ieCnt == 32) {
            createStyle();
            ieCnt = 0;
        }
        curSheet.addImport(url);
        curStyle.onload = function () { processIeLoad() };
    }
    var processIeLoad = function () {
        ieCurCallback();

        var nextLoad = ieLoads.shift();

        if (!nextLoad) {
            ieCurCallback = null;
            return;
        }

        ieCurCallback = nextLoad[1];
        createIeLoad(nextLoad[0]);
    }
    var importLoad = function (url, callback) {
        if (!curSheet || !curSheet.addImport)
            createStyle();

        if (curSheet && curSheet.addImport) {
            // old IE
            if (ieCurCallback) {
                ieLoads.push([url, callback]);
            }
            else {
                createIeLoad(url);
                ieCurCallback = callback;
            }
        }
        else {
            // old Firefox
            curStyle.textContent = '@import "' + url + '";';

            var loadInterval = setInterval(function () {
                try {
                    curStyle.sheet.cssRules;
                    clearInterval(loadInterval);
                    callback();
                } catch (e) { }
            }, 10);
        }
    }

    // <link> load method
    var linkLoad = function (url, callback) {
        var link = document.createElement('link');
        link.type = 'text/css';
        link.rel = 'stylesheet';
        if (useOnload)
            link.onload = function () {
                link.onload = function () { };
                // for style dimensions queries, a short delay can still be necessary
                setTimeout(callback, 7);
            }
        else
            var loadInterval = setInterval(function () {
                for (var i = 0; i < document.styleSheets.length; i++) {
                    var sheet = document.styleSheets[i];
                    if (sheet.href == link.href) {
                        clearInterval(loadInterval);
                        return callback();
                    }
                }
            }, 10);
        link.href = url;
        head.appendChild(link);
    }

    //>>excludeEnd('excludeRequireCss')
    cssAPI.normalize = function (name, normalize) {
        if (name.substr(name.length - 4, 4) == '.css')
            name = name.substr(0, name.length - 4);

        return normalize(name);
    }

    //>>excludeStart('excludeRequireCss', pragmas.excludeRequireCss)
    cssAPI.load = function (cssId, req, load, config) {

        (useImportLoad ? importLoad : linkLoad)(req.toUrl(cssId + '.css'), load);

    }

    //>>excludeEnd('excludeRequireCss')
    return cssAPI;
});
